The league says Assad's government has taken steps to comply with a regional initiative to stop the killing, but opposition activists, citing dozens more deaths, are incredulous over those remarks.

Arab League observers, in orange vests, talk to Syrians on Sunday in the… (SANA, European Pressphoto…)

Reporting from Beirut and Cairo — Syria's government has taken steps to comply with a regional initiative to end months of bloodshed, including pulling tanks out of cities and releasing nearly 3,500 detainees, the head of the Arab League said Monday. But he said gunfire continued and he called for a halt to the hostilities.

Syrian opposition activists disputed the assertion of significant progress, saying security forces had killed more than 150 people since Arab observers began work Dec. 27 to determine whether the government is ending a violent crackdown on dissent.

The reported death toll on Monday alone was as high as 26, said the Local Coordination Committees, a coalition that organizes protests and documents the violence. Most foreign journalists are barred from Syria, and it was not possible to verify the figures provided by the opposition.

The statement by Arab League Secretary-General Nabil Elaraby provided his first public comments on the findings of Arab observers, whose mission is the first of its kind for the 22-member regional bloc.

Elaraby defended the league's efforts, saying tanks and other military vehicles had pulled back to the outskirts of cities and residential areas, food aid had been provided and bodies had been recovered.

"Yes, there is still shooting, and yes, there are still snipers," Elaraby told reporters in Cairo, where the Arab League is based. But he said it was "hard to say who is shooting whom."

"There must be a complete cease-fire," he said.

Elaraby's remarks were met with disbelief by opposition activists in some of Syria's major trouble spots.

"Either the Arab observers are blind or they are working for the regime," said an activist in the strife-torn city of Homs, who gave his name as Abu Rami. He said there were checkpoints "full of soldiers" in the city and tanks hidden on its outskirts that could be back inside within minutes.

"This is not a withdrawal," he said.

The Arab League mission drew criticism even before it began last week. On Sunday, the Arab Parliament, a league advisory body, called for the withdrawal of the observers, saying their presence was providing cover for continued attacks on protesters by President Bashar Assad's regime.

Activists posted a video on YouTube on Monday that appeared to show a league observer in an orange vest being hustled away from a crowded street in the central city of Hama amid the crack of gunfire. Another video purported to show shooting erupting as a white vehicle containing observers drove through a demonstration in the northwestern town of Kfar Takharim. The shooters were not visible in the video,

whose authenticity could not be immediately confirmed.

The Local Coordination Committees said the league had "fallen victim to the regime's typical traps," and accused authorities of disguising soldiers in police uniforms and painting their vehicles to confuse the observers.

Activists welcomed the reported release of 3,484 detainees but said thousands of others remained behind bars, with more arrested every day.

Opposition groups contend that the observer mission is too small and too easily misled to effectively monitor a country of about 22 million. Elaraby said there were 70 monitors working in six cities, with 30 others expected soon.

He said the head of the mission, Sudanese Lt. Gen. Mohammed Ahmed Dabi, would report on progress by the end of the week, and Arab foreign ministers would meet as early as next week to review the findings and decide whether more monitors are needed.

Elaraby defended Dabi, whose judgment was questioned when he described conditions in Homs as "reassuring" despite weeks of amateur footage appearing to show heavy shelling and bloodied bodies in the city's opposition strongholds. The London-based rights group Amnesty International says Dabi headed a military intelligence branch in Sudan that was accused of severe abuses under his watch.

But Elaraby called Dabi "a capable military man with a clean reputation."

Syrian authorities insist that they are committed to the league's plan, which calls for the withdrawal of security forces from cities and residential areas, the release of political prisoners, free access for the media and dialogue with opposition groups. They blame the continued bloodshed on what they describe as foreign-backed armed terrorists, who they say have killed more than 2,000 security force members.

The state-run Syrian Arab News Agency reported that a law enforcement officer was killed Monday when a "terrorist group" opened fire on a patrol in front of Homs National Hospital.

What began in March as a largely peaceful uprising has become more violent in parts of the country where military defectors and some civilians have taken up arms against government security forces. U.N. officials say more than 5,000 people have been killed since March, and they have warned that the country could be on the brink of civil war.